Vectorize IndexOfAnyExcept for four values #73696
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Tagging subscribers to this area: @dotnet/area-system-memory Issue DetailsI took a look and the usage of
Since the first two got vectorized by @stephentoub in #73488 I've vectorized the 4 values case. Benchmarks: public class IndexOfAnyExcept
{
private string _whiteSpaces, _noWhiteSpaces;
[Params(1, 4, 16, 64, 256, 1024)]
public int Length { get; set; }
[GlobalSetup]
public void Setup()
{
_whiteSpaces = new string(' ', Length);
_noWhiteSpaces = new string('a', Length);
}
[Benchmark]
public int ImmediateMismatch() => _noWhiteSpaces.AsSpan().IndexOfAnyExcept(" \t\r\n");
[Benchmark]
public int NoMismatch() => _whiteSpaces.AsSpan().IndexOfAnyExcept(" \t\r\n");
}BenchmarkDotNet=v0.13.1.1845-nightly, OS=Windows 11 (10.0.22000.795/21H2)
AMD Ryzen Threadripper PRO 3945WX 12-Cores, 1 CPU, 24 logical and 12 physical cores
.NET SDK=7.0.100-preview.7.22377.5
[Host] : .NET 7.0.0 (7.0.22.37506), X64 RyuJIT AVX2
Job-OQFSEO : .NET 7.0.0 (42.42.42.42424), X64 RyuJIT AVX2
Job-main : .NET 7.0.0 (42.42.42.42424), X64 RyuJIT AVX2
It's clearly a tradeoff:
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stephentoub
reviewed
Aug 10, 2022
src/libraries/System.Private.CoreLib/src/System/SpanHelpers.T.cs
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Some pretty nice improvements! |
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The CI did not start... I am going to close and re-open the PR |
stephentoub
reviewed
Aug 11, 2022
| @@ -619,6 +680,9 @@ public static ReadOnlyMemory<char> AsMemory(this string? text, Range range) | |||
| case 3: | |||
| return IndexOfAnyExcept(span, values[0], values[1], values[2]); | |||
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| case 4: // common for searching whitespaces | |||
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Nit: (don't restart CI just for this)
Suggested change
| case 4: // common for searching whitespaces | |
| case 4: // common for searching ASCII whitespaces |
stephentoub
reviewed
Aug 11, 2022
| } | ||
| } | ||
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| return -1; | ||
| } | ||
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| [MethodImpl(MethodImplOptions.AggressiveInlining)] | ||
| private static int ComputeIndex<T>(ref T searchSpace, ref T current, Vector128<T> notEquals) where T : struct, IEquatable<T> |
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There are many other methods in this type, whereas this "ComputeIndex" is only relevant to LastIndexOfExcept. Consider renaming it accordingly.
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@stephentoub Since I currently can't merge #73768, I am going to merge this PR now and address your feedback later (renaming |
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I took a look and the usage of
IndexOfAnyExceptand the patterns are following:IndexOfAnyExcept(byte)- most frequentIndexOfAnyExcept(int),IndexOfAnyExcept(char)- sporadicIndexOfAnyExcept(" \t\r\n")- few placesSince the first two got vectorized by @stephentoub in #73488 I've vectorized the 4 values case.
Benchmarks:
It's clearly a tradeoff: